This post was written by Keith Dawson for UBM Tech’s community Web site All LED Lighting, sponsored by Philips Lumileds. It is archived here for informational purposes only because the All LED Lighting site may go dark at any time. This material is Copyright 2013-2015 by UBM Americas.


Soraa & the Rendering of Whites

There has been big pickup of the story we covered in February: the Penn State study that Soraa sponsored, demonstrating that blue-pumped LED light does not activate the optical brightening agents (OBAs) present in pretty much any product that the manufacturers want to appear whiter than white. We had introduced the topic of OBAs the previous September.

But in the more mainstream tech coverage, Soraa may not be getting its money's worth from the research sponsorship. Soraa's point, of course, is that its violet-pumped LEDs do activate OBAs. In other words, ordinary LEDs cause a problem that heretofore has not been widely discussed, and Soraa has the solution.

Essentially none of the widespread coverage I have seen mentions Soraa's solution. It's mostly just decrying how yellow our shirts will look.

Evolution of a meme
Quartz seems to have been the first tech blog to pick up on the news release that Penn State issued after Kevin Houser's research was published in LEUKOS. (Kudos to LEUKOS for making the full text available at that link; PDF here.)

The Quartz writeup does not mention Soraa -- either its sponsorship or the fact that the violet-pumped LEDs in the study were theirs.

Next pickup was by Gizmodo, and that's the one that brought wider notice to the story. The closest Giz's reporter comes to mentioning Soraa is the statement at the end of the piece: "Unfortunately, such specifically-tuned LEDs [with violet and UV in the spectrum] aren't the norm."

The Telegraph in the UK, linked above, again doesn't mention Soraa. The reporter did some research and presents a nice backgrounder on the history and chemistry of OBAs.

R&D Magazine goes over the research protocol in some detail, which makes for a useful summary. Again, no mention of Soraa's role in the study or its solution to the problem the study raises.

Soraa's take
LEDs Magazine published a piece yesterday by three Soraa researchers, including its CTO, Mike Krames. It's not mainstream media, but it will be widely read within our industry. The company is trying two approaches to framing the debate that it hopes Houser's research will touch off.

The first timber in the attempted framing defines quality of light (QoL) to include whiteness rendering as enhanced by OBAs. QoL, in Soraa's ideal would, would consist of CRI, R9, OBA activation, and, for directional lighting, beam angle and beam purity. This move is similar to Xicato's attempt to boost gamut area index as the best indicator of QoL, because its own light engines excel by this measure.

The second timber in the framing attempt is intended to diffuse the criticism that Soraa's GaN-on-GaN approach is too expensive, no matter its advantages. The company wants to introduce the metric of lumens per wafer. Soraa claims with good evidence that GaN-on-GaN already leads the pack by this metric, and will be ahead by a factor of five even when GaN-on-Si moves to 8-inch wafers.

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